JP2020189489A - Barrier laminate - Google Patents

Abstract

To provide a barrier laminate having paper as a base material, and excellent in steam barrier property, gas barrier property and transparency.SOLUTION: A barrier laminate includes a steam barrier layer and a gas barrier layer in this order at least on one surface of a paper base material. The barrier laminate is such that: the irregular freeness of pulp obtained by disintegrating the paper base material is 100 mL or more and 600 mL or less; the steam barrier layer contains a laminar inorganic compound, a cationic resin and an anionic binder; the laminar inorganic compound has a thickness of 200nm or less, and an aspect ratio of 50 or more; the gas barrier layer contains a water-soluble polymer; a moisture vapor transmission rate is 50 g/(m2 24h atm) or less; and a total light transmittance is 60% or more.SELECTED DRAWING: None

Description

The present invention relates to a barrier laminate using paper as a base material.

Packaging materials that use paper as a base material and have water vapor barrier properties and gas barrier properties (particularly oxygen barrier properties) have been conventionally used for packaging foods, medical products, electronic parts, and the like. As a method for imparting water vapor barrier property or gas barrier property to a paper base material, a method of laminating a synthetic resin film or a metal foil on the paper base material is common.

Since the conventional barrier packaging material is opaque, it is difficult to recognize the contents from the outside. Therefore, a transparent barrier packaging material has been desired so that the contents can be recognized from the outside.

Therefore, the development of a barrier material having transparency and using paper as a base material is being promoted. For example, Patent Document 1 describes a laminate in which an oxygen barrier layer and a heat seal layer are sequentially laminated on a paper support, and is a transparent barrier laminate that defines oxygen permeability, humidity permeability, and opacity. The body is disclosed.

Japanese Unexamined Patent Publication No. 2003-154609

However, the transparent barrier laminate described in Patent Document 1 has a structure in the order of a paper support, an oxygen barrier layer, and a heat seal layer (moisture-proof layer), and the thickness of the layer varies depending on the heat seal or the like. Therefore, there is room for further improvement in barrier performance.

The present invention has been made in view of the above circumstances. That is, an object of the present invention is to provide a barrier laminate having excellent water vapor barrier property, gas barrier property and transparency, using paper as a base material.

As a result of diligent studies on the materials constituting the laminate, the present inventors selected a paper base material having a specific range of irregular freeness of the dissociated pulp fibers as the base material, and selected a layered inorganic compound having a specific shape. It was found that inclusion in the water vapor barrier layer is effective in exhibiting water vapor barrier property and transparency. It was also found that it is effective to improve the barrier property by forming the layers in the order of the paper base material, the water vapor barrier layer and the gas barrier layer. The present invention has been completed based on such findings. That is, the present invention has the following configuration.

(1) A barrier laminate having a water vapor barrier layer and a gas barrier layer on at least one surface of the paper base material in this order, and the irregular freeness of the pulp fibers obtained by disintegrating the paper base material is 100 mL or more and 600 mL or less. The water vapor barrier layer contains a layered inorganic compound, a cationic resin and an anionic binder, the layered inorganic compound has a thickness of 200 nm or less and an aspect ratio of 50 or more, and the gas barrier layer contains a water-soluble polymer. containing and moisture permeability is at ^{50g / (m 2 · 24h ·} atm) or less, barrier laminate total light transmittance is equal to or less than 60%.

(2) The barrier laminate according to (1), wherein the content of the layered inorganic compound is 0.1% by mass or more and 80% by mass or less in the total solid content of the water vapor barrier layer.
(3) The barrier laminate according to (1) or (2) above, wherein the haze on the side where the water vapor barrier layer and the gas barrier layer are formed is 95% or less.
(4) Oxygen permeability is ^{10cc / (m 2 · 24h ·} atm) or less, the (1) to barrier laminate according to any one of (3).

(5) The anionic binder contains at least one of a styrene-butadiene copolymer having an acid group, a styrene-acrylic copolymer having an acid group, and an olefin / unsaturated carboxylic acid copolymer. The barrier laminate according to any one of (1) to (4) above.

(6) The barrier laminate according to any one of (1) to (5) above, wherein the cationic resin has a surface charge of 0.1 meq / g or more and 10 meq / g or less.
(7) The barrier laminate according to any one of (1) to (6) above, wherein the water-soluble polymer is polyvinyl alcohol or modified polyvinyl alcohol.

(8) The barrier laminate according to any one of (1) to (7) above, wherein the water vapor barrier layer contains at least one of mica, bentonite and kaolin as a layered inorganic compound.
(9) The barrier laminate according to any one of (1) to (8) above, which has a sealant layer on at least one outermost layer.
(10) The barrier laminate according to (9) above, wherein the sealant layer contains a biodegradable resin.
(11) The barrier laminate according to any one of (1) to (10) above, which is a packaging material.

According to the present invention, there is provided a barrier laminate having paper as a base material and having excellent water vapor barrier property, gas barrier property and transparency.

Hereinafter, embodiments of the present invention will be specifically described. The description of the constituent elements described below may be based on typical embodiments or specific examples, but the present invention is not limited to such embodiments.

The barrier laminate of the present embodiment has a water vapor barrier layer and a gas barrier layer in this order on at least one surface of the paper base material. The water vapor barrier layer and the gas barrier layer may be provided on only one side of the paper base material, or the water vapor barrier layer and the gas barrier layer may be provided on both sides of the paper base material.
Hereinafter, each layer constituting the barrier laminate of the present embodiment will be described.

[Paper base material]
The paper base material of the present embodiment contains pulp fibers of wood pulp as a main component. Here, the fact that the pulp fiber is the main component means that the pulp fiber is 50% by mass or more in the paper base material. The content ratio of the pulp fiber in the paper base material is preferably 50% by mass or more and 99.9% by mass or less, more preferably 70% by mass or more and 99.5% by mass or less, and 80% by mass or more and 99% by mass or less. The following is more preferable.

The wood pulp used for the paper base material is not particularly limited, and any wood pulp used for papermaking can be used. Examples of wood pulp include chemical pulps such as broad-leaved bleached kraft pulp (LBKP), coniferous bleached kraft pulp (NBKP), broad-leaved bleached sulphite pulp (LBSP), and coniferous bleached sulphite pulp (NBSP); stone ground pulp (GP). ), Pressurized stone ground pulp (PGW), refiner ground pulp (RGP), chemi-grand pulp (CGP), thermomechanical pulp (TMP), chemi-thermomechanical pulp (CTMP), etc. Mechanical pulp; sulfite pulp; waste paper pulp and the like can be mentioned. Considering the strength of the paper, it is preferable that the ratio of NBKP is high. In addition, synthetic fibers, non-wood fibers, and the like can be mixed with wood pulp as needed.

Pulp fibers generally have improved transparency as the beating process proceeds. Therefore, the paper base material of the present embodiment has an irregular freedom of 100 mL or more and 600 mL or less of the dissociated pulp fibers from the viewpoint of improving transparency. Here, the irregular freeness is measured by changing the pulp sampling amount from 3 g to 0.3 g and changing the JIS standard screen plate to 80 mesh wire in the Canadian standard freeness method specified in JIS P 8121: 2012. Freeness (degree of drainage). Further, the paper substrate is disintegrated in accordance with JIS P 820-1: 2012, and the irregular freeness of the pulp fiber obtained by the disaggregation is measured.
When the irregular freeness of the pulp fiber obtained by dissociating the paper base material is at least the above lower limit value, the dimensional stability of the paper base material becomes high and blurring is unlikely to occur. Can be maintained. The irregular freeness of the pulp fiber is more preferably 150 mL or more and 500 mL or less, and further preferably 200 mL or more and 400 mL or less. Known methods can be used for beating the pulp to adjust the anomalous freeness.

In order to improve the transparency of the paper base material, it is preferable to use further processed paper. Specifically, it is preferable to use glassine paper or glassine paper. Glassine paper refers to paper produced by beating pulp fibers to a high degree, then making paper, and processing it with a calendar or the like. Grafan paper refers to paper produced by beating pulp fibers to a higher degree than glassine paper, then making paper, and processing it with a calendar or the like. As the paper base material, glassine paper and glassine paper are preferable, and glassine paper is more preferable, from the viewpoint of transparency.

Internal chemicals such as sizing agents, paper strength enhancers, and colorants can be added to the paper base material as needed. The base paper obtained by subjecting these raw materials to the papermaking process is further calendered to obtain a paper base material having excellent transparency. In addition, a clearing agent can be applied if necessary. As the papermaking process, a known method can be used as appropriate. Further, the calendar equipment used for the calendar processing is not particularly limited, and known ones such as a machine calendar, a soft calendar, a super calendar, and a gloss calendar can be appropriately used. A known material such as a size press or a coater can be appropriately used for applying the clearing agent.

The basis weight of the paper base material is not particularly limited, but is preferably 20 g / m ² or more and 400 g / m ² or less, and more preferably 25 g / m ² or more and 320 g / m ² or less. The thickness of the paper base material is preferably 20 μm or more and 150 μm or less.
The density of the paper base material is preferably 1.0 g / cm ³ or more.

The air permeability of the paper substrate according to JIS P 8117: 2009 is preferably 1000 seconds / 100 mL or more, more preferably 10,000 seconds / 100 mL or more, and even more preferably 100,000 seconds / 100 mL or more.

[Water vapor barrier layer]
The water vapor barrier layer is a layer having a function of blocking the permeation of water vapor, and is laminated on the surface of the paper base material. The water vapor barrier layer contains a layered inorganic compound, a cationic resin and an anionic binder.

(Layered inorganic compound)
The form of the layered inorganic compound is flat. A water vapor barrier layer is formed when a mixed solution of a layered inorganic compound, a cationic resin and an anionic binder binder is prepared and coated on a paper substrate. In the water vapor barrier layer, the flat layered inorganic compounds are arranged in a state of being laminated substantially parallel to the plane (surface) of the paper base material. Then, in the plane direction, the area where the layered inorganic compound does not exist becomes smaller, so that the permeation of water vapor is suppressed. In addition, since the flat layered inorganic compounds exist in parallel to the plane of the paper substrate in the thickness direction, the water vapor in the layer permeates while bypassing the layered inorganic compound, and due to the maze effect, Permeation of water vapor is suppressed. As a result, the water vapor barrier layer can exhibit excellent water vapor barrier properties.

The layered inorganic compound has a thickness of 200 nm or less. The thickness of the layered inorganic compound is preferably 120 nm or less, more preferably 50 nm or less, further preferably 25 nm or less, and particularly preferably 10 nm or less. When the thickness of the layered inorganic compound is small, the number of laminated layered inorganic compounds in the water vapor barrier layer is large, so that high water vapor barrier property can be exhibited. Here, the thickness of the layered inorganic compound in the state of being contained in the water vapor barrier layer is obtained as follows. A magnified photograph of the cross section of the water vapor barrier layer is taken using an electron microscope. At this time, the magnification is such that about 20 to 30 layered inorganic compounds are contained in the screen. The thickness of each layered inorganic compound in the screen is measured. Then, the average value of the obtained thickness is calculated and used as the thickness of the layered inorganic compound.

The layered inorganic compound preferably has a length of 1 μm or more and 100 μm or less. When the length is 1 μm or more, the layered inorganic compounds are likely to be arranged parallel to the paper substrate. Further, when the length is 100 μm or less, there is little concern that a part of the layered inorganic compound protrudes from the water vapor barrier layer. The length of the layered inorganic compound is more preferably 50 μm or less, further preferably 30 μm or less, and particularly preferably 15 μm or less. Here, the length of the layered inorganic compound in the state of being contained in the water vapor barrier layer is obtained as follows. A magnified photograph of the cross section of the water vapor barrier layer is taken using an electron microscope. At this time, the magnification is such that about 20 to 30 layered inorganic compounds are contained in the screen. The length of each layered inorganic compound of the layered inorganic compound in the screen is measured. Then, the average value of the obtained lengths is calculated and used as the length of the layered inorganic compound. The length of the layered inorganic compound may be described by the expression of particle size.

The layered inorganic compound has an aspect ratio of 50 or more. When the aspect ratio is 50 or more, it is possible to achieve a predetermined water vapor barrier property. The aspect ratio of the layered inorganic compound is preferably 80 or more, more preferably 300 or more, and particularly preferably 500 or more. The larger the aspect ratio, the more the permeation of water vapor is suppressed and the water vapor barrier property is improved. Further, the larger the aspect ratio, the smaller the amount of the layered inorganic compound added. The upper limit of the aspect ratio is not particularly limited, and is preferably about 10,000 or less from the viewpoint of the viscosity of the coating liquid. Here, the aspect ratio is a value obtained by taking a magnified photograph of the cross section of the water vapor barrier layer using an electron microscope and dividing the average length of the obtained layered inorganic compound by the average thickness, as described above. Is.

Specific examples of layered inorganic compounds include mica such as mica and brittle mica, bentonite, kaolinite (kaolin mineral), pyrophyllite, talc, smectite, vermiculite, chlorite, septe chlorite, serpentine, and stirp. Examples include nomelane and montmorillonite.

Among these, from the viewpoint of improving the barrier property, it is preferable to contain one or more of mica, bentonite and kaolin, and mica or bentonite is more preferable. Specific examples of mica include synthetic mica (eg, swelling mica, non-swelling mica), white mica (mascobite), silk mica (serisite), gold mica (frocopite), black mica (biotight), and fluorine. Examples include gold mica (artificial mica), red mica, soda mica, vanajin mica, illite, chin mica, paragonite, and brittle mica. Further, as a specific example of bentonite, montmorillonite can be mentioned.

The content of the layered inorganic compound is preferably 80% by mass or less, more preferably 50% by mass or less, further preferably 30% by mass or less, and particularly preferably 20% by mass or less in the total solid content of the water vapor barrier layer. On the other hand, the content of the layered inorganic compound is preferably 0.1% by mass or more, more preferably 1% by mass or more, and further preferably 2% by mass or more. By increasing the aspect ratio of the layered inorganic compound and reducing the thickness, the content of the layered inorganic compound can be reduced. In addition, the strength of the water vapor barrier layer can be increased to prevent the layered inorganic compound from falling off from the water vapor barrier layer.

(Cationic resin)
The water vapor barrier layer contains a cationic resin. By containing the cationic resin in the water vapor barrier layer, the water vapor barrier property is greatly improved. The reason for this is as follows.
(1) Since the flat portion of the flat plate-like form is easily charged anionic and the edge portion is easily charged cationically, the layered inorganic compound may have a so-called card house structure in which the layered inorganic compounds are three-dimensionally aggregated with each other. Are known. Due to this card house structure, the aqueous dispersion of layered inorganic compounds has a very high viscosity.
(2) On the other hand, since the card house structure is easily broken when a force is applied by stirring or the like, the aqueous dispersion of the layered inorganic compound exhibits thixotropy.
(3) When an appropriate cationic resin is added to the aqueous dispersion of the layered inorganic compound, the cationic resin is adsorbed on the anionic flat portion of the layered inorganic compound, and the card house structure is destroyed. As a result, the three-dimensional aggregation of the layered inorganic compound is suppressed, and the flat layered inorganic compound is easily laminated in parallel with the plane of the paper substrate, leading to improvement in the water vapor barrier property.

Specific examples of cationic resins include polyalkylene polyamines, polyamide compounds, modified polyamide compounds, polyamide amine-epihalohydrin or formaldehyde condensation reaction products, polyamine-epihalohydrin or formaldehyde condensation reaction products, polyamide polyurea-epihalohydrin or formaldehyde condensation. Reaction products, polyamine polyurea-epihalohydrin or formaldehyde condensation reaction products, polyamideamine polyurea-epihalohydrin or formaldehyde condensation reaction products, polyamide polyurea compounds, polyamine polyurea compounds, polyamide amine polyurea compounds and polyamide amine compounds, polyethylene Examples thereof include imine, polyvinylpyridine, amino-modified acrylamide compound, polyvinylamine, polydiallyldimethylammonium chloride and the like.

The surface charge of the cationic resin is preferably 0.1 meq / g or more and 10 meq / g or less, and more preferably 0.2 meq / g or more and 5 meq / g or less. When the surface charge of the cationic resin is within the above range, the card house structure can be destroyed, and the anionic binder described later can coexist appropriately. The surface charge of the cationic resin is measured by the method described below.

The polymer as a sample is dissolved in water to obtain a solution having a polymer concentration of 1 ppm. 0.001N sodium polyethylene sulfonate is added dropwise to the solution using a charge analyzer Mutek PCD-04 (manufactured by BTG), and the amount of charge is measured.

The content of the cationic resin in the water vapor barrier layer may be appropriately selected according to the type of the layered inorganic compound and the anionic binder used in the water vapor barrier layer, but from the viewpoint of improving the barrier property, the layered inorganic compound 100 It is preferably 1 part by mass or more and 300 parts by mass or less, more preferably 3 parts by mass or more and 250 parts by mass or less, further preferably 5 parts by mass or more and 200 parts by mass or less, and 10 parts by mass or more and 150 parts by mass or less. It is particularly preferable, and most preferably 20 parts by mass or more and 100 parts by mass or less.

The content of the cationic resin is preferably 0.1 part by mass or more and 20 parts by mass or less, and more preferably 0.3 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the anionic binder of the water vapor barrier layer. It is more preferably 1 part by mass or more and 10 parts by mass or less.

(Anionic binder)
Since the binder in the water vapor barrier layer is anionic, the water vapor barrier property is further improved. As described above, the flat portion of the layered inorganic compound is anionic, but when the cationic resin is adsorbed, the surface becomes cationic. Therefore, the affinity with the anionic binder is enhanced.

As the anionic binder, a binder modified with a monomer containing a carboxylic acid group is preferable. Polymers that form the skeleton of the anionic binder include styrene / butadiene copolymers, styrene / acrylic copolymers, methacrylate / butadiene copolymers, acrylic nitrile / butadiene copolymers, and olefin / unsaturated carboxylic acids. Examples thereof include a system copolymer and an acrylic ester type polymer. Among these, styrene-butadiene-based copolymers, styrene-acrylic copolymers, and olefin-unsaturated carboxylics have good water resistance, good elongation, and are less likely to crack the coating layer due to cracking. It is preferable to contain one or more of the acid-based copolymers.

Styrene-butadiene copolymers include styrene compounds such as styrene, α-methylstyrene, vinyltoluene, pt-butylstyrene and chlorostyrene, and 1,3-butadiene and isoprene (2-methyl-1,3). -Butadiene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene and other butadiene compounds, and other compounds copolymerizable with these, obtained by emulsifying and polymerizing a monomer. It is a copolymer. Styrene is preferable as the styrene compound, and 1,3-butadiene is preferable as the butadiene compound.

Styrene-acrylic copolymers include styrene compounds such as styrene, α-methylstyrene, vinyltoluene, pt-butylstyrene, and chlorostyrene, and acrylic acid, methacrylic acid, (meth) acrylic acid ester, and (meth) acrylic acid ester. ) Emulsion polymerization of a monomer composed of acrylic compounds such as acrylamide propane sulfonic acid and sulfoalkyl sodium salt (meth) acrylic acid (alkyl group having 2 or more and 3 or less carbon atoms) and other compounds copolymerizable with these. It is a copolymer obtained by the above. As the styrene-based compound, styrene is preferable, and as the acrylic-based compound, acrylic acid, methacrylic acid, acrylic acid ester, and methacrylic acid ester are preferable, and acrylic acid and acrylic acid ester are more preferable. The (meth) acrylic acid ester is preferably an acrylic acid alkyl ester, and the alkyl group preferably has 1 to 6 carbon atoms.

Olefin / unsaturated carboxylic acid-based copolymers include olefins, especially α-olefins such as propylene or ethylene, acrylic acid, methacrylic acid, crotonic acid, silicic acid, itaconic acid, fumaric acid, maleic acid, butentricarboxylic acid. Unsaturated polycarboxylic acid alkyl esters having at least one carboxy group, such as unsaturated carboxylic acids such as acids, itaconic acid monoethyl esters, fumaric acid monobutyl esters and maleic acid monobutyl esters, and copolymerizable with them. It is a copolymer obtained by emulsifying and polymerizing a monomer composed of other compounds.
As the olefin, ethylene or α-olefin is preferable, and ethylene is more preferable.
Further, as the unsaturated carboxylic acid monomer, acrylic acid, methacrylic acid, itaconic acid, fumaric acid and the like are suitable.
Specific examples of the olefin / unsaturated carboxylic acid-based copolymer include, for example, an aqueous dispersion of an ammonium salt of an ethylene / acrylic acid copolymer, Zyxene® AC or the like (copolymerization ratio of acrylic acid 20%, Sumitomo). It is commercially available as (manufactured by Seika Co., Ltd.) and can be easily obtained and used.

When the skeleton polymer does not have an acid group, the anionic binder is obtained by copolymerizing the above skeleton polymer with a monomer containing an acid group such as a carboxy group and modifying it. be able to.
The copolymerization ratio of the monomer containing an acid group such as a carboxy group in the anionic binder is preferably 1 mol or more and 50 mol% or less.

The weight average molecular weight of the anionic binder is preferably 10,000 or more and 10 million or less, and more preferably 100,000 or more and 5 million or less, from the viewpoint of the viscosity of the coating liquid.

The content ratio of the anionic binder is not particularly limited, but is preferably 20% by mass or more, more preferably 50% by mass or more, further preferably 60% by mass or more, and particularly preferably 70% by mass or more in the total solid content of the water vapor barrier layer. It is preferable, and 80% by mass or more is most preferable.

In the water vapor barrier layer, in addition to the layered inorganic compound, the cationic resin and the anionic binder, a dispersant, a surfactant, a defoaming agent, a wetting agent, a dye, a color adjusting agent, a thickener and the like are appropriately added as necessary. It can be added.

The thickness of the water vapor barrier layer is preferably 1 μm or more and 30 μm or less, and more preferably 3 μm or more and 20 μm or less. The coating amount of the water vapor barrier layer is preferably 1 g / m ² or more and 30 g / m ² or less, and more preferably 3 g / m ² or more and 20 g / m ² or less as a solid content.

[Gas barrier layer]
The gas barrier layer is a layer having a function of mainly blocking the permeation of oxygen gas, and is laminated on the water vapor barrier layer. The gas barrier layer contains a water-soluble polymer.

(Water-soluble polymer)
Examples of the water-soluble polymer include polyvinyl alcohol, modified polyvinyl alcohol, starch and its derivatives, cellulose derivatives, polyvinylpyrrolidone, urethane resins, polyacrylic acid and salts thereof, casein, polyethyleneimine and the like.

Among these, completely saponified or partially saponified polyvinyl alcohol or modified polyvinyl alcohol is preferable because it has more excellent gas barrier properties. Examples of the modified polyvinyl alcohol include ethylene-modified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, and diacetone-modified polyvinyl alcohol.

The content of the water-soluble polymer is preferably 50% by mass or more and 100% by mass or less, and more preferably 70% by mass or more and 100% by mass or less in the total solid content of the gas barrier layer.

Similar to the water vapor barrier layer, the gas barrier layer may contain the above-mentioned layered inorganic compound. When the layered inorganic compound is contained in the gas barrier layer, the content of the layered inorganic compound is not particularly limited, but is preferably about 1 part by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the water-soluble polymer of the gas barrier layer. More preferably, it is 5 parts by mass or more and 15 parts by mass or less. The layered inorganic compound is preferably at least one selected from the group consisting of mica, bentonite and kaolin from the viewpoint of improving the barrier property. The layered inorganic compound contained in the gas barrier layer may be of the same type as the layered inorganic compound contained in the water vapor barrier layer, or may be of a different type.

In addition to the water-soluble polymer and the layered inorganic compound, the gas barrier layer is appropriately added with a pigment, a dispersant, a surfactant, a defoaming agent, a wetting agent, a dye, a color tone adjusting agent, a thickener, and the like. It is possible.

The thickness of the gas barrier layer is preferably 0.1 μm or more and 10 μm or less, and more preferably 0.5 μm or more and 5 μm or less. The coating amount of the gas barrier layer is preferably 0.1 g / m ² or more and 10 g / m ² or less, and more preferably 0.5 g / m ² or more and 5 g / m ² or less as a solid content. ..

[Barrier laminate]
The barrier laminate of the present embodiment has a water vapor barrier layer and a gas barrier layer in this order on at least one surface of the paper base material. Since the gas barrier layer is a relatively thin layer, the film becomes more uniform when formed on the flat surface of the water vapor barrier layer than when it is formed directly on the paper substrate, and the gas barrier function originally possessed by the water-soluble polymer is exhibited. It can be effectively demonstrated. Further, as described above, the water vapor barrier layer physically suppresses the permeation of water vapor by arranging the flat layered inorganic compounds in a state of being laminated substantially parallel to the plane of the paper base material. Not only that, the permeation of gas such as oxygen can be suppressed. Therefore, by forming the gas barrier layer on the water vapor barrier layer, the gas barrier performance against oxygen and the like can be improved more effectively.

Barrier laminate, in view of a packaging material having an oxygen gas barrier property, it is preferable that the oxygen transmission rate is at ^{10cc / (m 2 · 24h ·} atm) or ^{less, 5cc / (m 2 · 24h} · atm) or less Is more preferable.
The barrier laminate is preferably in view of a packaging material having a water vapor barrier property, moisture permeability is ^{50g / (m 2 · 24h ·} atm) or ^{less, 40g / (m 2 · 24h} · atm) The following is more preferable. Moisture permeability can be measured according to JIS Z 0208: 1976.

From the viewpoint of a transparent packaging material, the barrier laminate preferably has a total light transmittance of 60% or more, and more preferably 80% or more. The total light transmittance can be measured according to JIS K 7361-1: 1997.
Further, from the viewpoint of a transparent packaging material, the barrier laminate preferably has a haze of 95% or less on the side where the water vapor barrier layer and the gas barrier layer are formed, and more preferably 75% or less. .. The haze can be measured from the side where the water vapor barrier layer and the gas barrier layer are formed according to JIS K 7136: 2000.

(Manufacturing method of barrier laminate)
In the barrier laminate, the water vapor barrier layer forming coating liquid is first applied on the paper base material to form the water vapor barrier layer, and then the gas barrier layer forming coating liquid is applied to form the gas barrier layer. Can be manufactured by forming. Each layer may be formed by sequentially coating and drying the coating liquid, or may be formed by drying after simultaneous multi-layer coating.

The solvent of the coating liquid is not particularly limited, and water or an organic solvent such as ethanol, isopropyl alcohol, methyl ethyl ketone or toluene can be used.

The coating equipment for applying the coating liquid to the paper substrate is not particularly limited, and known equipment can be used. Examples of the coating equipment include a blade coater, a bar coater, an air knife coater, a slit die coater, a gravure coater, a micro gravure coater, and a gate roll coater. In particular, for forming the water vapor barrier layer, a coater that scrapes the coated surface, such as a blade coater, a bar coater, an air knife coater, and a slit die coater, is preferable in that it promotes the orientation of the layered inorganic compound.

[Sealant layer]
The barrier laminate has a water vapor barrier layer and a gas barrier layer in this order on at least one surface of the paper base material, and further forms a sealant layer on at least one outermost layer of the barrier laminate. You may. That is, the sealant layer may be formed on the gas barrier layer on the side where the water vapor barrier layer and the gas barrier layer are formed, or may be formed on the paper substrate on the side where the water vapor barrier layer and the gas barrier layer are not formed. It may be formed on both sides.
The sealant layer is a layer that melts and adheres by heating or ultrasonic waves, and is a layer that can bond the barrier laminates to each other by heat sealing or the like.

The sealant layer can be formed by laminating synthetic resins such as polyethylene, polypropylene, an ethylene-vinyl acetate polymer, and a polyvinyl acetate polymer by a melt extrusion laminating method or a dry laminating method. The sealant layer can also be formed by applying an emulsified dispersion of a synthetic resin such as polyethylene, polypropylene, an ethylene-vinyl acetate polymer, or a polyvinyl acetate polymer.

The sealant layer preferably contains a biodegradable resin. Specific examples of the biodegradable resin are not particularly limited, for example, polylactic acid (PLA), polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), 3-hydroxybutanoic acid / 3-hydroxyhexanoic acid. Copolymers (PHBH) and the like can be mentioned.

The thickness of the sealant layer is preferably 1 to 50 μm, more preferably 3 to 35 μm. The amount of the sealant layer formed is preferably 1 to 50 g / m ² and more preferably 3 to 30 g / m ² as the solid content.

In the barrier laminate of the present embodiment, since the water vapor barrier layer contains the layered inorganic compound, the cationic resin and the anionic binder, the layered inorganic compound in the water vapor barrier layer does not form a card house structure. Since it is laminated in a uniformly dispersed state, it has excellent water vapor barrier properties. Further, since the surface of the water vapor barrier layer is formed smoothly, it is possible to uniformly form the gas barrier layer on the surface, and the gas barrier property is excellent.

The barrier laminate of the present embodiment can be suitably used as a packaging material for foods, medical products, electronic parts, etc. by taking advantage of the above-mentioned excellent water vapor barrier properties and gas barrier properties. Further, since the barrier laminate of the present embodiment has resistance to cracking, it can be suitably used as a material for flexible packaging.

Hereinafter, the barrier laminate of the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. Unless otherwise specified, "parts" and "%" in Examples and Comparative Examples indicate "parts by mass" and "% by mass", respectively.

The raw materials used in the examples and comparative examples are as follows.
(1) Paper base material Graphan paper: Basis weight 30 g / m ² , thickness 25.6 μm, density 1.17 g / m ³ , air permeability 99999 seconds or more / 100 mL, manufactured by Oji F-Tex Co., Ltd., JIS P 820-1 : Anomalous freeness 250 mL of pulp fiber dissociated according to 2012
Bleached kraft paper: Basis weight 60 g / m ² , Thickness 75.9 μm, Density 0.79 g / m ³ , Air permeability 16 seconds / 100 mL, Oji Materia, JIS P 820-1: 2012 Anomalous freedom of pulp fiber 700mL
(2) Layered inorganic compound Mica: Swellable mica, particle size 6.3 μm, aspect ratio about 1000, thickness about 5 nm, solid content 7%, product name: NTO-05, Kaolin manufactured by Topy Industries Co., Ltd .: Engineered kaolin, Particle size 9.0 μm, aspect ratio 80-100, thickness about 100 nm, solid content 100%, product name: Varisurf HX, manufactured by Imeris Minerals (3) Cationic resin Modified polyamide resin: solid content 53%, product Name: SPI203 (50), manufactured by Taoka Chemical Industry Co., Ltd., surface charge 0.4 meq / g
(4) Anionic binder Olefin / unsaturated carboxylic acid resin: Water-based emulsion of ethylene-acrylic acid copolymer, solid content 29.3%, Product name: Zyxen AC, styrene-butadiene copolymer manufactured by Sumitomo Seika Co., Ltd. Combined: Water-based emulsion of acid-modified SBR latex, solid content 47.3%, Product name: LX407S12, Styrene-acrylic copolymer manufactured by Nippon Zeon Co., Ltd .: Water-based emulsion of styrene-acrylic resin, solid content 53.8%, Product name: Harville C-3, manufactured by Daiichi Paint Mfg. Co., Ltd. (5) Water-soluble polymer Ethylene copolymer polyvinyl alcohol: Excelval AQ4104, Kurare company Polyvinyl alcohol: Fully saponified polyvinyl alcohol, Product name: Poval PVA117, Clare (6) Sealant layer Low-density polyethylene film: LLDPE film, T.I. U.S. X FCS, 30 μm thick, Polybutylene succinate manufactured by Mitsui Chemicals Tohcello Co., Ltd .: PBS, Product name: Bio PBS FZ71, manufactured by Mitsubishi Chemical Corporation, 30 μm thick

(Example 1)
<Water vapor barrier layer coating liquid>
To 29.3 parts of an aqueous dispersion of a layered inorganic compound (swellable mica), 100 parts of an aqueous emulsion (Zyxen AC) of an ethylene-acrylic acid copolymer was added with stirring. To this, 2.93 parts of a modified polyamide resin (SPI203 (50)) was added, and the mixture was stirred. Further, 0.35 part of a 25% aqueous ammonia solution was added and stirred. Further, diluted water was added to bring the solid content concentration to 25% to prepare a coating liquid for a water vapor barrier layer.

<Coating liquid for gas barrier layer>
A 10% aqueous solution of ethylene copolymer polyvinyl alcohol (Excelval AQ4104) was prepared and used as a coating liquid for a gas barrier layer.

The paper base material was graphan paper, and the coating liquid for the water vapor barrier layer was applied with a Mayer bar so that the coating amount was 6 g / m ^2, and then dried at 120 ° C. for 1 minute in a hot air dryer. Further, a coating liquid for a gas barrier layer was applied thereto with a Mayer bar so as to be ² g / m ^2, and then dried in a hot air dryer at 120 ° C. for 1 minute to obtain a barrier laminate.

(Example 2)
A barrier laminate was produced in the same manner as in Example 1 except that the coating amount of the coating liquid for the water vapor barrier layer was 12 g / m ² .

(Example 3)
A barrier laminate (layer structure: gas barrier layer / water vapor barrier layer / paper base material /) in the same manner as in Example 1 except that the coating liquid for the water vapor barrier layer and the coating liquid for the gas barrier layer were applied to both sides. A water vapor barrier layer / gas barrier layer) was prepared.

(Example 4)
100 parts of the ethylene-acrylic acid copolymer emulsion was changed to 61.9 parts of the acid-modified SBR latex emulsion (LX407S12) to prepare a coating liquid for the water vapor barrier layer, and the coating liquid for the gas barrier layer was polyvinyl alcohol (Poval). A barrier laminate was produced in the same manner as in Example 1 except that it was changed to PVA117).

(Example 5)
Change 29.3 parts of the aqueous dispersion of swelling mica to 71.5 parts of a 41% aqueous solution of engineered kaolin (Varisurf HX), and change 2.93 parts of the modified polyamide resin to 2.26 parts to change the steam barrier. A barrier laminate was produced in the same manner as in Example 1 except that the layer coating liquid was prepared.

(Example 6)
To 40 parts of ethylene copolymer polyvinyl alcohol (Excelval AQ4104) as a water-soluble polymer, 66.7 parts of an aqueous dispersion (NTO-05) of a layered inorganic compound (swelling mica) and diluted water were added and stirred, and the solid content was stirred. A barrier laminate was obtained in the same manner as in Example 1 except that an aqueous solution having a concentration of 10% was prepared and used as a coating liquid for a gas barrier layer.

(Example 7)
A barrier laminate was produced in the same manner as in Example 1 except that the LLDPE film was laminated and applied as the sealant layer by dry lamination.

(Example 8)
A barrier laminate was obtained in the same manner as in Example 1 except that polybutylene succinate was laminated and applied as a sealant layer by melt extrusion lamination.

(Comparative Example 1)
A barrier laminate was produced in the same manner as in Example 1 except that the paper base material was bleached kraft paper.

(Comparative Example 2)
A barrier laminate was produced in the same manner as in Example 1 except that the coating liquid for the water vapor barrier layer and the coating liquid for the gas barrier layer were not applied.

[Evaluation methods]
The following performances were evaluated using the barrier laminates obtained in Examples and Comparative Examples.
(1) Moisture permeability (water vapor permeability)
Measurement was performed by JIS Z 0208: 1976 (cup method) B method (40 ° C. ± 0.5 ° C., relative humidity 90% ± 2%) with the water vapor barrier layer and the gas barrier layer inside. As the criterion of the moisture ^{permeability,} if 50g / m 2 · 24h · atm or less, it is determined that there is utility as water vapor barrier layer.

(2) Oxygen Permeability The measurement was performed at 23 ° C. and 50% RH conditions using an oxygen permeability measuring device (OX-TRAN2 / 20 manufactured by MOCON). Incidentally, as a criterion for the oxygen permeability, when 10cc ^/ m 2 · 24h · atm or less, it is determined that there is utility as a gas barrier layer.

(3) Total light transmittance The total light transmittance of the barrier laminate was measured according to JIS K 7361-1: 1997 and used as an index of transparency. If the total light transmittance is 60% or more, it is judged to be good.

(4) Haze According to JIS K 7136: 2000, the haze of the barrier laminate on the side where the water vapor barrier layer and the gas barrier layer were formed was measured and used as an index of transparency. When the sealant layer was further provided, the measurement was performed on the side where the sealant layer was formed. If the haze was 95% or less, it was judged to be good.

Table 1 shows the evaluation results of the barrier laminates of Examples 1 to 8 and Comparative Examples 1 and 2.

As is clear from Table 1, the barrier laminates of Examples 1 to 8 were excellent in water vapor barrier property, gas barrier property and transparency. On the other hand, the barrier laminate of Comparative Example 1 was inferior in transparency because bleached kraft paper having an irregular freeness of more than 600 mL was used as the paper base material. Further, the barrier laminate of Comparative Example 2 did not have a water vapor barrier layer and a gas barrier layer, and was inferior in barrier performance.

Claims (11)

A barrier laminate having a water vapor barrier layer and a gas barrier layer on at least one surface of a paper substrate in this order.
The irregular freeness of the pulp fiber obtained by dissociating the paper substrate is 100 mL or more and 600 mL or less.
The water vapor barrier layer contains a layered inorganic compound, a cationic resin and an anionic binder.
The layered inorganic compound has a thickness of 200 nm or less and an aspect ratio of 50 or more.
The gas barrier layer contains a water-soluble polymer and
Moisture permeability is at ^{50g / (m 2 · 24h ·} atm) or less,
A barrier laminate characterized by having a total light transmittance of 60% or more. The barrier laminate according to claim 1, wherein the content of the layered inorganic compound is 0.1% by mass or more and 80% by mass or less in the total solid content of the water vapor barrier layer. The barrier-type laminate according to claim 1 or 2, wherein the haze on the side where the water vapor barrier layer and the gas barrier layer are formed is 95% or less. Oxygen permeability is ^{10cc / (m 2 · 24h ·} atm) or less, barrier laminate according to any one of claims 1 to 3. Claimed that the anionic binder contains at least one of a styrene-butadiene copolymer having an acid group, a styrene-acrylic copolymer having an acid group, and an olefin / unsaturated carboxylic acid copolymer. Item 2. The barrier laminate according to any one of Items 1 to 4. The barrier laminate according to any one of claims 1 to 5, wherein the cationic resin has a surface charge of 0.1 meq / g or more and 10 meq / g or less. The barrier laminate according to any one of claims 1 to 6, wherein the water-soluble polymer is polyvinyl alcohol or modified polyvinyl alcohol. The barrier laminate according to any one of claims 1 to 7, wherein the water vapor barrier layer contains at least one of mica, bentonite and kaolin as a layered inorganic compound. The barrier laminate according to any one of claims 1 to 8, which has a sealant layer in at least one outermost layer. The barrier laminate according to claim 9, wherein the sealant layer contains a biodegradable resin. The barrier laminate according to any one of claims 1 to 10, which is a material for packaging.